By: Roman Sasik, Ph.D.
Chlorella is a genus of unicellular aquatic organisms that recently acquired a “superfood” status, in part because of its complete amino acid profile and a high omega-3 DHA and EPA fatty acid content. It has also been reported to lower blood pressure in humans, lower serum cholesterol, boost immunity, and even fight cancer.
It appears the superfood status of Chlorella is richly deserved. Even though Chlorella as an organism has been around for billions of years, for obvious reasons it could not have been a significant part of human diet and therefore it should be considerd an industrial-era food and should be treated with caution for this reason alone. It wasn’t until recently that we understood how Chlorella does its magic. In a 2002 paper, Armstrong et al.  discovered a lipopolysaccharide (LPS) in the cellular wall of Chlorella. LPS is an endotoxin found on the surface of all gram-negative bacteria such as E. coli or Salmonella and is a potent immune system activator. When LPS binds to receptors on the surface of macrophages (phagocytic cells of the innate immune system), it activates them and induces them to release pro-inflammatory cytokines IL-1β, tumor necrosis factor TNFα, and nuclear factor-kappa B (NF-κB) . Chlorella, in effect, puts our innate immunity on high alert via LPS, an endotoxin it happens to share with some lethal bacteria. Too much LPS leads to sepsis, which we would be well advised to avoid, but even low doses of Chlorella may be ill advised if they are chronic. While activated immune system may be beneficial in situations such as during an infectious disease outbreak, one must ask what happens to us when we make chlorella a regular part of diet, indeed, a food. Chronic exposure to LPS leads to chronic systemic inflammation, which is not a desirable state of affairs, as the readers of this blog know. Specifically, systemic LPS-activated macrophages in the brain have been implicated in progressive degeneration of dopaminergic neurons and are responsible for Parkinson’s disease . But wait! Isn’t Chlorella at the bottom of the aquatic food chain? Some hapless organism must be eating it, so why can’t we? It turns out that animals that eat algae in general, such as the horseshoe crab or shrimp, have evolved a mechanism, a unique protein, to bind and neutralize LPS. We have not. In the case of Chlorella we see another manifestation of a well-known evolutionary story, that of grains and birds that eat them, and people who eat the birds. People, unlike birds, do not do well when eating grains directly. It is the same with Chlorella, shrimp that eat it, and people who eat the shrimp.
If this were not enough to dissuade you from using Chlorella as food, there is also potential for contamination with viruses. Giant ones . Normally, a virus contains genetic information of a handful of viral proteins. Chlorella viruses have more than three hundred genes, most of which encode proteins of unknown function. The potential for harmful interaction of these proteins with normal functioning of human cells is real. If the history of another fallen superfood of the recent past, that of Klamath Lake cyanobacteria, is any guide, I expect to hear a lot more about Chlorella viruses in the future. As the use of Chlorella for food increases under pressure from industrial producers and distributors, the likelihood of viral contamination increases as well. We would do well to stick to time-tested superfoods with a complete amino acid profile and high content of DHA and EPA – fish.
People who for whatever reason refuse to get their DHA and EPA from animal sources would do well if they supplemented their diet with Chlorella-derived omega-3 fatty acids rather than by eating whole Chlorella. This is assuming that Chlorella fatty acid extracts are free of LPS and other toxic substances.
 Armstrong PB, Armstrong MT, Pardy RL, Child A, Wainwright N., Immunohistochemical demonstration of a lipopolysaccharide in the cell wall of a eukaryote, the green alga, Chlorella, Biol Bull. 2002 Oct;203(2):203-4.
 Hsu HY, Jeyashoke N, Yeh CH, Song YJ, Hua KF, Chao LK, Immunostimulatory bioactivity of algal polysaccharides from Chlorella pyrenoidosa activates macrophages via Toll-like receptor 4, J Agric Food Chem. 2010 Jan 27;58(2):927-36.
 Qin L, Wu X, Block ML, Liu Y, Breese GR, Hong JS, Knapp DJ, Crews FT, Systemic LPS causes chronic neuroinflammation and progressive neurodegeneration, Glia. 2007 Apr 1;55(5):453-62.
 Van Etten JL, Unusual life style of giant chlorella viruses, Annu Rev Genet. 2003;37:153-95.